Bus driver circuits apply signals to a data transmission bus which transmits them to data receivers. In this respect, the bus is part of a system of data transmitters and data receivers; for example, the data transmitters can be sensors and the data receivers control or indicating circuits.
Conventionally, the information transmitted by the bus is digital signals, the presence of a signal value of 1 being recognized, for example, if a positive voltage of 5V is applied to the bus. The bus driver circuit produces this +5V at the core of the bus. Since the core of the bus is typically connected with a large number of bus driver circuits, interference may cause a voltage higher than +5V to occur on the bus. In this case, it is necessary to take steps to assure that this higher voltage does not lead to an excessively heavy load for the source supplying the +5V. The higher voltage might also cause the voltage at the bus core to be tied to a certain level and not be able to be altered again.
One object of my invention is to provide a bus driver circuit without the above-mentioned problems which may be produced as an integrated circuit requiring a small amount of space on a semiconductor chip.